At a stroke, it's got a product authorized for a specific use in 27 countries.Tandem Diabetes Care (TNDM 4.25%) had some encouraging news to report on the regulatory front Thursday, and after it hit the headlines investors piled into the stock. At the end of the day the highly specialized healthcare company's share price had risen in excess of 4%, good enough to top the 1.7% rise of the benchmark S&P 500 index.Crucial approval grantedTandem announced Thursday morning that it had won an important approval fr ...